1) Gluten free should mean a product that is made without any food substance or derivative that contains gluten. Since the research is still not conclusive, items that contain quantities of gluten below a certain level should not contain the gluten free label. Since gluten sensitivity is so variable, it is essential for Celiacs and their families to know that they can rely on the designation on the label, ie that gluten free means without gluten as opposed to containing trace amounts.
2) Reading all labels carefully. Utilizing pda software and cheat-sheets for known products. We spend at least 10-15 minutes of every shopping trip deciphering labels.
3) Our numbers are skewed because we purposely buy those products for our daughter, but I would estimate that 10-15% of purchases carry the gluten free label.
4) The presence of gluten free strongly influences purchase choices, especially when similar products are available, and one has the label and the other does not.